This invention relates in general to the field of filters, and more specifically to a PLL loop filter that can be integrated. The loop filter can be used in a fully integrated PLL design such as a PLL synthesizer, etc.
The biggest component in a type 2 PLL (using a three-state charge-pump) is the capacitor that provides the zero in the PLL transfer function. Given this capacitor""s typical large capacitance value, it is not possible to integrate it, which in turn adds extra cost in manufacturing the PLL circuit. A need thus exist in the art for a filter architecture that allows for the integration of this capacitor and therefore provides for improved and manufacturability of the PLL.